1. Field of the Invention
The present invention relates to a semiconductor integrated circuit.
2. Description of the Related Art
In order to suppress a malfunction of a semiconductor integrated circuit due to electrostatic discharge or other kinds of noise (which is also referred to as “EMI: Electro-Magnetic Interference”) received from a human body or from another device, various countermeasures have been proposed for products mounting such a semiconductor integrated circuit. Such countermeasures can be roughly classified into two types: for example, one is that such a countermeasure is provided to a portion that differs from the semiconductor integrated circuit, e.g., is provided to a housing of the product, internal wiring, or the like; and the other is that such a countermeasure is provided to the semiconductor integrated circuit itself. In recent years, there is an increased demand for a semiconductor integrated circuit having improved EMS (Electro-Magnetic Susceptibility).
For example, Patent Document 1 (Japanese Patent Application Laid Open No. 2005-252123) discloses a technique for employing an RC filter to remove noise contaminating a semiconductor integrated circuit. In this technique, a first semiconductor chip that corresponds to a semiconductor integrated circuit to be protected and a second semiconductor chip on which an RC filter is formed are provided in a layered structure. With such an arrangement, an external signal is input to the semiconductor integrated circuit formed on the first semiconductor chip via the RC filter formed on the second chip.
However, with such a configuration disclosed in Patent Document 1, the RC filter is not capable of effectively removing noise directly contaminating a pad formed on the first semiconductor chip configured as a semiconductor integrated circuit. Furthermore, such an arrangement requires an additional chip used to mount the RC filter. This leads to an increased parts cost and a higher assembly cost.